1. Field of the Invention
Embodiments of the present invention relate to the use and storage of biogas and, more particularly, to underground storage of biogas.
2. Background Description
Biogas, which is generated when bacteria degrade biological material in the absence of oxygen in a process known as anaerobic digestion, is composed primarily of methane and carbon dioxide and, typically, trace constituents of hydrogen sulfide, mercaptans, vinyl chloride and/or other volatile organic compounds. Biogas represents both an environmental liability and a unique renewable energy resource.
Exemplary sources of biological material that can generate biogas are found at (or in) marshes, landfills (waste disposal facilities), septic tanks, farms (e.g., cattle and/or dairy farms), sewage treatment facilities, paper mills, olive oil mills, industrial food production facilities (e.g., potato processing, canning operations, and slaughter houses). Bioreactors can generate biogas at these locations or facilities. When the source of the biogas is a landfill, the biogas may be referred to as landfill gas.
Concerns that are often associated with biogas relate to odors, air quality impacts and explosion hazards. If released to the atmosphere untreated, biogas is also a potent greenhouse gas contributing to global climate change.
The methane component of biogas contains energy that could be used, for example, to generate electricity, heat buildings, fuel industrial processes, and/or run vehicles. Utilization of energy from biogas not only mitigates the local environmental impact of biogas, but also advantageously reduces consumption of fossil fuels that would otherwise be required to generate an equal amount of energy. Collection and use of biogas represents a significant opportunity to reduce greenhouse gas emissions to the atmosphere.
Due to the presence of carbon dioxide, nonmethane organics, and other contaminants, biogas generally cannot be stored in tanks for future use in an economically viable manner. We have discovered that biogas can be stored underground, generally at a lower cost. Embodiments of the present invention are directed to these, as well as other, important ends.